Accuracy and linearity problems with DHT11

I have a AM2302 temp/humidity sensor and two DHT11, The AM2302 and DHT11 read different temperatures, with a discrepancy of ~2.2°C at 21°C. I have put in a correct factor in the DHT11’s (|float - 2.2), but the error is non-linear.

I know that DHT11 have a reputation for poor reliability/quality, but does this include issues with linearity?